test/call_suite_aggrs: - refactored generator code a bit to be simpler, write cleaner output, have better shareability and clarity - added rtypes w/ default value nil to config.lua, to self document - shared some code under test/common/ - fixed nonemptyaggrs sigs and cases.h (accidentally overwritten with cases having empty aggrs)

Daniel Adler <dadler@uni-goettingen.de>
Tassilo Philipp <tphilipp@potion-studios.com>
Olivier Chafik <olivier.chafik@gmail.com>
Erik Mackdanz <erikmack@gmail.com>
Masanori Mitsugi <mitsugi@linux.vnet.ibm.com>
Bernhard Urban-Forster <beurba@microsoft.com>